Method of manufacturing filled polyurethane particles

Abstract

The present invention relates to a method of manufacturing a solids-incorporating polymer comprising the steps of: I) providing an aqueous polymer dispersion, the dispersion comprising crystallizing polyurethane particles having a mean particle size of ≤500 nm and further comprising inorganic particles; II) storing the dispersion of step I) at a temperature of ≤0° C. until a precipitate is formed; III) Isolating the precipitate of step II) and IV) removing water from the isolated precipitate of step III), thereby obtaining a water-depleted precipitate. The invention also relates to a solid particulate composition which is obtainable by the method and the use of the composition as a build material in additive manufacturing processes, as a coating, an adhesive or as a rubber.

1 . A method of manufacturing a solids-incorporating polymer comprising:
 I) Providing an aqueous dispersion, the dispersion comprising polymer particles having an intensity-based harmonic mean particle size of the hydrodynamic diameter (Z-Average), as determined by dynamic light scattering, of ≤500 nm;   II) Storing the dispersion of step I) at a temperature of ≤0° C. until a precipitate is formed;   III) Isolating the precipitate of step II) to obtain an isolated precipitate;   IV) Removing water from the isolated precipitate of step III), thereby obtaining a water-depleted precipitate;   wherein the dispersion of step I) further comprises inorganic particles,   and wherein the polymer is a crystallizing polyurethane.   
     
     
         2 . The method according to  claim 1 , wherein the inorganic particles have an intensity-based harmonic mean particle size of the hydrodynamic diameter (Z-Average), as determined by dynamic light scattering, of ≤100 nm. 
     
     
         3 . The method according to  claim 1 , further comprising:
 V) Grinding the water-depleted precipitate of step IV) into particles with a number-based mean particle size, as determined by optical microscopy, of ≤500 μm.   
     
     
         4 . The method according  claim 1 , wherein the dispersion of step I) has a polymer solids content of ≥20 weight-% to ≤60 weight-%, based on the total weight of the dispersion. 
     
     
         5 . The method according to  claim 1 , wherein step II) is conducted at a temperature of from ≥−40° C. to ≤−8° C. 
     
     
         6 . The method according to  claim 1 , wherein step III) comprises a filtration step and/or a decanting step. 
     
     
         7 . The method according to  claim 1 , wherein step IV) is conducted at a temperature of ≤2° C. 
     
     
         8 . The method according to  claim 1 , wherein the water-depleted precipitate of step IV) has a water content of from ≥0.1 weight-% to ≤5 weight-%, based on the total weight of the water-depleted precipitate. 
     
     
         9 . The method according to  claim 1 , wherein the water-depleted precipitate of step IV) has an inorganic particle content of from ≥2 weight-% to ≤50 weight-%, based on the total weight of dried precipitate. 
     
     
         10 . The method according to  claim 1 , wherein a polymer of the polymer particles in the dispersion of step I) has a number-average molecular weight Mn, determined by gel permeation chromatography, of ≥30000 g/mol. 
     
     
         11 . The method according to  claim 1 , wherein the inorganic particles in the dispersion of step I) comprise silicon dioxide, titanium dioxide, aluminum oxide, titanium nitride, tungsten nitride, tungsten carbide, carbon black, graphene, carbon nanotubes, metals, sheet silicates, clays comprising organic cations, non-white metal oxides, or a mixture of at least two of the aforementioned particle types. 
     
     
         12 . The method according to  claim 1 , wherein the dispersion of step I) is free from solid polyisocyanates and/or elements from subgroups 5 and 6 of the periodic system of elements in which the particular element has an oxidation number of at least +4. 
     
     
         13 . A solid particulate composition, obtained by a method according to  claim 1 , comprising particles, wherein the particles of the composition comprise a matrix of a crystallizing polyurethane,
 wherein a number-based mean particle of the composition, as determined by optical microscopy, is ≤10 mm, and wherein inorganic particles are embedded within the matrix to form embedded inorganic particles having an number-based mean particle size, as determined by electron microscopy, of ≤1000 nm.   
     
     
         14 . The composition of  claim 13 , wherein
 the particles of the composition have a major axis representing the largest dimension of each particle and a minor axis representing the smallest dimension of each particle, the dimensions being determined by optical microscopy,   wherein the mean ratio of major axis length to minor axis length is from ≥1:0.01 to ≤1:1,   and wherein the number-based mean particle size, as determined by optical microscopy, is ≤10 mm.   
     
     
         15 . A build material in an additive manufacturing process, a coating, an adhesive or a rubber, comprising the solid particulate composition according to  claim 13 .